The controversial experiments, that were also funded by other German automotive corporations, such as Daimler and BMW, have sparked public outcry.

The major German car maker Volkswagen has reportedly co-financed tests of car exhaust fumes on monkeys and humans, in order to prove that its diesels were clean.

The experiments are said to have been carried out back in 2014 in the United States by the “European Research Association for Environment and Health in the Transport Sector” (EUGT), which is founded by Daimler, VW, BMW and Bosch companies.

All in all, ten monkeys and some 25 healthy human beings are reported to have been subject to the experiments.

The tests haven’t had any negative consequences for the health of either the animals or the humans, but the news has caused public outcry, with many people arguing that those responsible for the initiative must be punished.

The Lower Saxony Minister of Economics and VW Supervisory Board Bernd Althusmann described the experiments as “absurd and inexcusable.”

In addition to a full inquiry and a comprehensive report, he expects “hard personal consequences” for those involved in the tests, German Der Spiegel magazine quoted him as saying.

“Those who came up with such ideas jointly with other car makers should be held accountable,” Althusmann said.

VW has already apologized for the experiments conducted on monkeys.

“We are convinced that the scientific method, chosen at that time, was wrong. It would have been better to give up the idea from the very outset,” VW said.

However, the news about tests on humans have added fuel to the fire and sparked harsh criticism among social media users.

According to Der Spiegel, Nitrogen dioxide (NO2) is the pollutant whose measurements were manipulated by VW for years to officially comply with the legally required limits for diesel vehicles in the United States.

The pollutant may negatively affect respiratory organs of animals and humans and cause cough, breathing difficulties and eye irritation.